Organic materials rotate the plane of polarization of incident linearly polarized light. Therefore, by measuring the optical rotating power thereof, the materials can be identified or optical isomers can be distinguished.
For these purposes, the optical rotating power of the materials has been measured, for example, according to Japanese Industrial Standard (JIS) K 0063 (pages 669 to 673).
In optical rotating power measurements, since a signal to be detected is very low, a S/N ratio that is higher than in general measurements has been demanded. To meet this demand, conventional optical rotating power measurements start after waiting for the sample to reach a predetermined temperature and stabilize at the predetermined temperature, as disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2000-46732.
With this procedure, however, it takes much time until the sample reaches the predetermined temperature.
There has been a strong demand in the optical rotating power measurement field for a technique that realizes both speedup and S/N ratio improvement. Conventionally, such a technique was not found.